Tests: added Ruby threading tests.

test/ruby/threads/config.ru

@@ -0,0 +1,13 @@
+app = Proc.new do |env|
+    delay = env['HTTP_X_DELAY'].to_f
+
+    sleep(delay)
+
+    ['200', {
+        'Content-Length' => 0.to_s,
+        'Rack-Multithread' => env['rack.multithread'].to_s,
+        'X-Thread' => Thread.current.object_id.to_s
+    }, []]
+end
+
+run app